Role of proteinuria reduction in the progression of IgA nephropathy

Proteinuria has been shown to play a causal role in the progression towards ESRD of IgA nephropathy (IgAN). We demonstrated that steroids are effective in reducing proteinuria and preserving renal function. Aim: to evaluate the long-term effect of steroids in IgAN patients (6th year evaluation) and better clarify the role of proteinuria reduction in slowing down the progression. Methods: multicenter randomized controlled trial of 86 adult IgAN patients with serum creatinine less than or equal to 1.5 mg/dL and moderate proteinuria. They received either supportive therapy or methylprednisolone 1-g i.v. for three days at months 1, 3, and 5, plus oral prednisone (0.5 mg/kg every other day for six months). Results: Proteinuria significantly decreased in the treated patients (from 2.0 +/- 0.60 g/24 h at baseline to 1.0 +/- 0.68 g/24 h at six months) and remained stable till the 6th year (0.67 +/- 0.5 g/24 h); it slightly decreased in the control group. Six-year renal survival was significantly better in the steroid than in the control group: 9 patient (20.9%) in the steroid group and 15 (34.8%) in the control group reached the primary endpoint of a 50% increase in serum creatinine from baseline. Five controls and none of the steroid-treated patients started dialysis. Steroid-treated patients did not experience any major side effects during follow-up. Conclusions: Steroids significantly reduce proteinuria and protect against renal function deterioration in IgAN patients. Early reduction of proteinuria could also be marker of a persistent reduction in its levels over time and of a better outcome in the long term.